This is a Chrome app to allow browser-based Javascript code to pass raw data to a supported printer. It is aimed at developers of web-based point-of-sale systems where server-side printing is not feasable.

This has been developed for use with a USB receipt printer, with an ESC/POS command generator (escpos-php) providing the binary data.

Web-based and cloud-based point-of-sale systems have their benefits, but adding printing is difficult.

• Using system printing and a vendor driver produces terrible output
• Server-side printing and 'cloud' do not mix well

This app bridges the gap, by exposing a websocket on localhost. A web-page can then retrieve binary print data from the server, and pass it to the app for printing.

Only USB receipt printers are currently supported.

• Networked printers may be supported in future.
• Serial/Parallel printers may be accessed via a USB adaptor.
• CUPS/IPP/Windows shared printers are out of scope at this stage, please hook in directly via USB.

Raw printing for Chrome is loaded with vendor/product ID's for the following printers:

• Epson TM-T20
• PL2305 Parallel Port
• Winbond Virtual Com Port.

If your USB printer is not listed, please create a new issue to request support. Because of the way Chrome app permissions work, please include the USB vendor ID and product ID.

This app is simply a connector. In theory, any page description language is supported, provided that you are able to generate it, and your printer can understand it.

This application is not yet available in the Chrome store, so the installation steps are a bit unusual:

• Under chrome://extensions, tick developer mode, and 'load unpacked extension', and locate this folder.
• Launch the extension, select your printer
• If not listed, find the USB product, vendor ID, add it to manifest.md, and restart.
• Click print
• If it doesn't print, check the error log and see the notes within the app for the basic things to check.
• In particular, unload the usblp kernel module if applicable as it will claim the USB interface to the printer.

A small example web-page available under example/, which will print a "Hello World" receipt in ESC/POS if the raw printint app is running, with an ESC/POS printer configured. Steps to try it out:

• Run the app
• Add a printer
• Open the example web page
• Click a few buttons and hope for output.

This was tested on an Epson TM-T20.

Pull requests are welcome and appreciated. This project is quite new, please see the issue tracker for ideas of things to work on.